Relationships between chemical components of veld herbage and animal growth

The relationships between certain chemical components of fertilized and unfertilized Cymbopogon-Themeda summer veld herbage, herbage intake by lactating cows and steers and daily gain of pre-weaned calves or steers, were determined in the summer rainfall area of the Republic of South Africa. The herbage was represented by a wide range of grass species with, according to the literature, different palatabilities. ve correlations that were found for the relationships of concentrations of some of the amino acids and sulphur (S) content with crude protein (CP) content of the veld herbage, indicate that supplementation of high quality summer veld herbage with ruminally undegraded histidine, valine, isoleucine and S-containing amino acids may be beneficial for fast growing ruminants. rrelation between digestible dry matter intake by the grazing steers (DDMIW), expressed in g per kg W0.75 day−1, and the average daily gain (ADG) of the steers (g day−1), was highly significant (P < 0.01; r = 0.87). The relationship between DDMIW by lactating cows and the ADG of their calves was not significant (P > 0.05; r = 0.44). Highly significant (P < 0.01) correlations were found between ADG of steers and respectively CP content and acid detergent fibre (ADF) content of the pasture. (r = 0.95; r = −0.86). The relationship between neutral detergent fibre (NDF) content of the herbage and the ADG of the steers was significant (P < 0.05; r = −0.68). The CP content of the herbage that the cows grazed was correlated highly significantly (P < 0.01; r = 0.69) with the ADG of the unweaned calves. No significant relationships could be found between ADG of the calves and the ADF and NDF contents respectively of the pasture that their mothers grazed (P > 0.05; r = −0.36 and r = −0.21). the conditions described, some of these relationships can be used reliably for the prediction of potential animal growth on summer veld herbage.